NASA 2001 Mars Odyssey page 1 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Present knowledge of HEND efficiency for neutrons and gamma- rays Workshop “The First year of HEND operations on the NASA Odyssey Mars Orbiter” Moscow, Russia May 20-22, 2002

NASA 2001 Mars Odyssey page 2 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Schematic design of HEND

NASA 2001 Mars Odyssey page 3 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Schematic design of sensor LD (Left) and SD (Right) for epithermal neutrons

NASA 2001 Mars Odyssey page 4 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Components of SD and LD sensors

NASA 2001 Mars Odyssey page 5 Workshop HEND Russian Aviation and Space Agency Institute for Space Research He 3 +n→H 3 +p+ E total E total = MeV E(H 3 ) = 1/4 E total = MeV E(p) = 3/4 E total = MeV 1/4QTRITON3/4QPROTON

NASA 2001 Mars Odyssey page 6 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Measured spectrum of counts of MD sensor is represented in 16 channels

NASA 2001 Mars Odyssey page 7 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Schematic design of stilbene and CsI scintillation detectors

NASA 2001 Mars Odyssey page 8 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Neutron Recoil proton Registration of neutrons on recoil protons Registration of neutrons on recoil protons

NASA 2001 Mars Odyssey page 9 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Proton Separation between background and recoil protons is done by help of anticoincidence circuit based on CsI crystal which surrounds stilbene detector in direction of open space

NASA 2001 Mars Odyssey page 10 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Photon Distinguishing between neutron and gamma signal in stilbene crystal is done by help of electronic pulse shape in the stilbene crystal

NASA 2001 Mars Odyssey page 11 Workshop HEND Russian Aviation and Space Agency Institute for Space Research PERFORMANCE: LD: 10.0 eV MeV MD: 0.4 eV keV SD: 0.4 eV keV IN/SC/N: 850 keV – 15.0 MeV IN/SC/G:60 keV– 2.0 MeV OUT/SC:30 keV – 1.0 MeV

NASA 2001 Mars Odyssey page 12 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Response functions of LD, MD and SC/neutron sensors allow to fit data of #2, #3 and #4 periapses with function of type  E -  HEND energy range

NASA 2001 Mars Odyssey page 13 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Calibration facilities of Joint Institute of Nuclear Research in Dubna (Russia) were used for physical calibrations of 1st and 2nd Flight Units of HEND

NASA 2001 Mars Odyssey page 14 Workshop HEND Russian Aviation and Space Agency Institute for Space Research PHYSICAL CALIBRATIONS: The measured sensitivity has met agreement with the numerical simulation results

NASA 2001 Mars Odyssey page 15 Workshop HEND Russian Aviation and Space Agency Institute for Space Research PHYSICAL CALIBRATIONS: The difference between numerical calculation and measured value for SD sensor takes place due to not taking account of HEND model as an assembly

NASA 2001 Mars Odyssey page 16 Workshop HEND Russian Aviation and Space Agency Institute for Space Research PHYSICAL CALIBRATIONS: The difference between effective cross section of SC detectors of 1st and 2nd Flight Units is resulted from different electrical thresholds and it could be easily taken into account

NASA 2001 Mars Odyssey page 17 Workshop HEND Russian Aviation and Space Agency Institute for Space Research Future tasks:  Mathematical simulation: building of HEND numerical model as an assembly building of HEND numerical model as an assembly building of HEND numerical model with taking into account the spacecraft model building of HEND numerical model with taking into account the spacecraft model  Physical calibration of HEND instrument with respect to gamma-rays and charge particles  Establishing of correspondence between Flight end Qualification Units